Statistical presentation in international scientific publications 7. Conclusions Malcolm Campbell Lecturer in Statistics, School of Nursing, Midwifery & Social Work, The University of Manchester Statistical Editor, Health & Social Care in the Community

26 March 2008Statistical presentation - 7. Conclusions2 7. Conclusions Contents 7.1 General conclusions 7.2 Statistical conclusions 7.3 Final thoughts

26 March 2008Statistical presentation - 7. Conclusions3 7.1 General conclusions 1 Planning a draft paper – Peat et al (2002, p 16) SectionQuestion to be answered PurposeExpected length* IntroductionWhy did you start?Summarise context of study and state aims clearly 1 page MethodsWhat did you do?Give enough details for study to be repeated 2-3 pages ResultsWhat did you find?Describe study sample and use data analyses to answer the aims 2-3 pages Tables & figures What do the results show? Clarify the results3-6 tables or figures DiscussionWhat does it mean?Interpret findings in context of literature and describe potential impact on health care 2-3 pages ReferencesWho else has done important work? Cite most relevant and recent literature references Total12-20 pages * words [!], A4 paper, font size 10-12, 1.5 line spacing

26 March 2008Statistical presentation - 7. Conclusions4 General conclusions 2 General advice on submitting papers to journals Choose the most appropriate journal –impact factor –scope of journal, and readership will paper be of interest? –even try reading some papers… (ho, ho, ho) Read the journal’s instructions to authors –layout and structure –style of referencing –word count Type double-spaced with each table or figure on separate page –include list of tables and figures Number the pages –title page as page 1 authors names on this page only –Abstract on page 2 with title repeated at top If necessary, use an English spell-checker –and if possible a native English- speaking proof reader

26 March 2008Statistical presentation - 7. Conclusions5 7.2 Statistical conclusions 1 General advice on reporting methods Think about the reader –international? statistically aware? numerate? Follow the standard IMRaD structure –it helps with your thinking! Clearly describe the study design and sampling –and inclusion/exclusion criteria Justify your sample size –just as you did to get your research funded State the statistical methods and software used Make sure what you write is readable!

26 March 2008Statistical presentation - 7. Conclusions6 Statistical conclusions 2 General advice on reporting results Report on missing data Report numbers (percents), means (SDs) and medians (ranges or IQRs) –to appropriate numbers of decimal places Report test results in full with supporting statistics –even if non-significant, assuming test was important Make sure any tables and figures can stand alone Be logical and consistent Make sure what you write is readable!

26 March 2008Statistical presentation - 7. Conclusions7 Reporting numbers Golden rules for reporting numbers – Peat & Barton (2005) In text, give numbers –with units (eg cm) as numbers –< 10 as words –≥ 10 as numbers –at start of sentence as words Use a 0 before decimal point for numbers < 1 No space between number and % sign but space between number and unit Use 2 decimal places for most test statistics & correlations* Rules for sample size & %: –< 20: use numbers not %s –< 100: % to nearest whole number –> 100: % to 1 decimal place Use one more decimal place than unit of measurement when reporting descriptive statistics Report last decimal place if 0* Report p-values to 3 decimal places or 2 significant figures, or p < if very small* * My rules!

26 March 2008Statistical presentation - 7. Conclusions8 7.3 Final thoughts 1 How to ensure your paper is rejected, Wager et al (2002) Adopt a ponderous and wordy style and try to make everything ambiguous –after all, if readers can understand the stuff, it can’t be that clever Insert references to all your previous publications at random –especially if they bear no relation to the current work Ignore the journal’s conventions about the structure of Abstract and paper –ensure that you include some choice results in the Methods and plenty of discussion in the Results

26 March 2008Statistical presentation - 7. Conclusions9 Final thoughts 2 How to ensure your paper is rejected, Wager et al (2002) On no account read the instructions to authors Make sure your pages are not numbered –and if possible, submit them out of order Insert figures and tables into the text as the whim takes you Choose an obscure style for references (and definitely not one of your chosen journal) –remember not to check your references and ensure that several are incomplete Make sure that you exceed the maximum length by at least 1000 words and two tables

26 March 2008Statistical presentation - 7. Conclusions10 Final thoughts 3 How to ensure your paper is NOT rejected, Campbell (2008) And you felt that those final thoughts from Wager et al (2002) were silly? –unfortunately, they all occur in real life –but you won’t follow their advice, will you? If you want one single reference to help you… –J. Peacock and S. Kerry (2007). Presenting Medical Statistics from Proposal to Publication: a step-by-step guide. Oxford University Press, Oxford. how to present “statistical information” in research proposals, reports and papers, covering study design, sample size calculation, data processing, data analysis and results… wonderful